Thesis for the Degree of Doctor of Philosophy - DTU Orbit

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Paper IV Hansen,V., Roos, P., Aldahan, A., Hou, X., Possnert, G. Partition of Iodine ( 129 I and 127 I) Isotopes in Soil and Sediment. Journal of Environmental Radioactivity xxx (2011) 1-9
Partition of iodine ( 129 I and 127 I) isotopes in soils and marine sediments Violeta Hansen a, *, Per Roos a , Ala Aldahan b,c , Xiaolin Hou a , Göran Possnert d a Risø National Laboratory for Sustainable Energy, NUK-202, Technical University of Denmark, Frederiksborgvej 399, P.O.B. 49, DK-4000 Roskilde, Denmark b Department of Earth Science, Uppsala University, SE-758 36 Uppsala, Sweden c Department of Geology, United Arab Emirates University, Al Ain, United Arab Emirates d Tandem Laboratory, Uppsala University, SE-751 21 Uppsala, Sweden article info Article history: Received 16 May 2011 Received in revised form 12 July 2011 Accepted 19 July 2011 Available online xxx Keywords: Iodine-129, 127 Speciation Iodine humic substances ICP-MS AMS 1. Introduction abstract The bioavailability of radioactive pollutants in the environment plays a decisive role in relation to the environmental pollutant impact, and in particular to the internal and external doses to humans. The bioavailability of a pollutant is generally related to its speciation and accordingly, chemical species of radionuclides can be a determining factor affecting their environmental impact and hazard. Iodine-129 can also be released in reactor accidents due to its high volatility, and can in this context serve as a retrospective tracer shedding new light on the environmental behavior of the radiologically much more important, but also much more shortlived 131 I. Practices of speciation analyses for radionuclides are a relatively recent implement and the literature data are rather * Corresponding author. Technical University of Denmark, Risø National Laboratory for Sustainable Energy NUK-202, Frederiksborgvej 399, P.O.B. 49, 4000 Røskilde, Denmark. E-mail address: violeta.hansen@risoe.dk (V. Hansen). 0265-931X/$ e see front matter Ó 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.jenvrad.2011.07.005 Journal of Environmental Radioactivity xxx (2011) 1e9 Contents lists available at ScienceDirect Journal of Environmental Radioactivity journal homepage: www.elsevier.com/locate/jenvrad Natural organic matter, such as humic and fulvic acids and humin, plays a key role in determining the fate and mobility of radioiodine in soil and sediments. The radioisotope 129 I is continuously produced and released from nuclear fuel reprocessing plants, and as a biophilic element, its environmental mobility is strongly linked to organic matter. Due to its long half-life (15.7 million years), 129 I builds up in the environment and can be traced since the beginning of the nuclear era in reservoirs such as soils and marine sediments. Nevertheless, partition of the isotope between the different types of organic matter in soil and sediment is rarely explored. Here we present a sequential extraction of 129 I and 127 I chemical forms encountered in a Danish soil, a soil reference material (IAEA-375), an anoxic marine sediment from Southern Norway and an oxic sediment from the Barents Sea. The different forms of iodine are related to water soluble, exchangeable, carbonates, oxides as well as iodine bound to humic acid, fulvic acid and to humin and minerals. This is the first study to identify 129 I in humic and fulvic acid and humin. The results show that 30e56% of the total 127 I and 42e60% of the total 129 I are associated with organic matter in soil and sediment samples. At a soil/ sediment pH below 5.0e5.5, 127 I and 129 I in the organic fraction associate primarily with the humic acid while at soil/sediment pH > 6 129 I was mostly found to be bound to fulvic acid. Anoxic conditions seem to increase the mobility and availability of iodine compared to oxic, while subaerial conditions (soils) reduces the availability of water soluble fraction compared to subaqueous (marine) conditions. Ó 2011 Elsevier Ltd. All rights reserved. scarce. The concentrations of the radioactive isotope 129 I have been and are still increasing in the environment since the beginning of the atomic era in the late nineteen forties (Hou et al., 2009a; Englund et al., 2010; Aldahan et al., 2007a; Lo’pez-Gutie’rrez et al., 2004). As iodine is a biophilic element its distribution in the environment merits investigation (Hou et al., 2003, 2009a; Aldahan et al., 2007a). The isotope has a half-life of (15.7 million years) and it is naturally formed by cosmic-ray-induced spallation of xenon in the upper atmosphere, spontaneous fission of 238 U and in minor quantities, by neutron bombardment of tellurium in the geosphere. Thermal neutron induced fission of 235 U is another minor natural source of 129 I in the lithosphere. Presently, the source of additional 129 I in the environment is mainly from human nuclear activity such as nuclear reprocessing facilities, nuclear weapons testing and accidents associated with nuclear power plants. Contributions of 129 I from nuclear weapon tests (57e63 kg of 129 I), the Chernobyl accident (1.3e6 kgof 129 I) and nuclear power plants are relatively insignificant (Hou et al., 2009a; Englund et al., 2010 and Andersson et al., 2009). Discharges from nuclear reprocessing facilities into the marine and atmospheric environments represent Please cite this article in press as: Hansen, V., et al., Partition of iodine ( 129 I and 127 I) isotopes in soils and marine sediments, Journal of Environmental Radioactivity (2011), doi:10.1016/j.jenvrad.2011.07.005
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Chemical Speciation Analysis and En
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Thesis for the Degree of Doctor of
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Abstract This thesis deals with che
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environment since they reflect the
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organiske jodformer. Adsorption af
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None of this would have been possib
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Abbreviations and acronyms b+ - pos
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3.1 Analytical Development………
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Table 1 Some properties of iodine P
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In soils/sediments iodine occurs as
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Table 2 Nuclear properties of iodin
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Liquid scintillation counting (LSC)
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The bioavailability of radioactive
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data (Englund et al., 2010; Hou et
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2. Analytical procedures used in th
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2.3 Quantification of total iodine
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Fig. 5 Quantification of total iodi
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iodate were measured by counting 12
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Fig. 6 Sequential extraction proced
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a Fig. 8 Calibration curve for (a)
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experiment was subjected to combust
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Table 7 Adsorption of iodine specie
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numbers 11-14), which is about the
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marine environment from nuclear fue
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127 I - (ppb) 127 IO3 - (ppb) a b 1
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Although the oxygen concentration d
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129 I TBq 2,00E+00 1,80E+00 1,60E+0
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• Adsorption of iodine species on
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Reference Aldahan A, Kekli A, Possn
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Fuge R& Johnson C. 1986. The geoche
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Lo´pez-Gutie´rrez JM, Garcı ´a-
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Shinohara K. 2004. Measurement and
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http://www.irsn.fr/EN/news/Document
Page 67 and 68: Review Analytica Chimica Acta 632 (
Page 69 and 70: Table 1 Nuclear properties and prod
Page 71 and 72: Fig. 2. Liquid discharges of 129 I
Page 73 and 74: Fig. 5. Schematic diagram and pictu
Page 75 and 76: 129 I in iodide and iodate is then
Page 77 and 78: Fig. 8. Diagram of air sampler for
Page 79 and 80: Fig. 10. Iodine L3-edge (a) and K-e
Page 81 and 82: analysis of 129 I in water sample a
Page 83 and 84: Yi P, Aldahan A, Hansen V, Possnert
Page 85 and 86: FIGURE 1. Sampling sites (the red s
Page 87 and 88: FIGURE 3. Horizontal distribution o
Page 89 and 90: FIGURE 5. Time series data of 129 I
Page 91 and 92: Environmental Science & Technology
Page 93 and 94: prepared using KI and KIO3. No diff
Page 95 and 96: of their contribution to the Baltic
Page 97 and 98: Fig. S-1 Sampling sites (the red so
Page 99 and 100: Fig. S-3 Vertical distribution of I
Page 101 and 102: Fig. S-5 Marine discharges function
Page 103 and 104: Fig.S-7 Relationship between I-129
Page 105 and 106: Table S-1 Results of I-129 and I-12
Page 107 and 108: S17
Page 109 and 110: Paper III Hansen,V., Yi, P., Hou, X
Page 111 and 112: conversion process between iodide a
Page 113 and 114: Table 1 Analytical results of 129 I
Page 115 and 116: August April I-129 iodide ( 10 8 at
Page 117: References Aldahan A, Kekli A, Poss
Page 121 and 122: Norway (Table 1). CTD-casts with ox
Page 123 and 124: 5. Discussion 5.1. Separation of hu
Page 125 and 126: In the present study 40e60% of 129
Page 127 and 128: Hutta, M., Gora, R., 2003. Novel st
Page 129 and 130: Analysis of 129 I and 127 I in arch
Page 131 and 132: et al., 2002). Due to the fact that
Page 133 and 134: espectively. The iodine was leached
Page 135 and 136: salinities in the same area. Apart
Page 137 and 138: North Sea. 129 I/ 127 I ratios in w
Page 139 and 140: Table 2 Analytical results of 129-I
Page 141 and 142: 129 I/ 127 I 1,40E-07 1,20E-07 1,00
Page 143 and 144: References Aldahan A, Englund E, Po
Page 145 and 146: O’Dowd, C.; Jimenez, J. L.; Bahre
Page 147 and 148: Iodine ( 129 I and 127 I) speciatio
Page 149 and 150: water in winter by molecular oxygen
Page 151 and 152: 0.2 M KNO3. The effluent and the wa
Page 153 and 154: maximum values is at 0.03-0.06×10
Page 155 and 156: into the English Channel from the L
Page 157 and 158: References Aldahan A, Kekli A, Poss
Page 160 and 161: Risø-PhD-81(EN)
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Thesis for the Degree of Doctor of Philosophy - DTU Orbit

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